1. Field of the Invention
The invention relates to an object detection device for detecting an object.
2. Description of the Related Art
Conventionally, devices described in Japanese Patent Application Publication No. 2008-276308 (JP-A-2008-276308), Japanese Patent Application Publication No. 2008-238927 (JP-A-2008-238927) and the like are available for detecting objects. JP-A-2008-276308 describes a video processing device that detects an optical flow from a video that was captured by an imaging element mounted on a movable body. The forgoing video processing device includes a calculation unite for dividing the frames contained in the video into a plurality of regions and calculating the optical flow of each region under different conditions, and a parameter decision unit that changes at least the mode or condition of the division of the frames in accordance with the state of the movable body. This device changes the frame interval between the target frame and the reference frame for detecting the optical flow depending on whether the object to be detected is at a short distance or a long distance.
When detecting objects using the forgoing device, the magnitude of optical flow will unexpectedly increase under circumstances where the image of the object moves considerably in the lateral direction such as when the object is far off in the lateral direction from the center of the image or when the movable body is to make a large turn. Accordingly, the accuracy in detecting the object under the circumstances may be reduced.
In addition, the device described in JP-A-2008-238927 detects a moving captured at different times by a wide-angle camera to calculate the moving vector of each block of the captured images.
When detecting objects using the moving vector (displacement) of images as with the forgoing device, it is difficult to detect the object if the movement of such object is not apparent in the image. Nonetheless, in wide-angle images captured by a wide-angle camera, the image area of a center region relative to the size of the space captured in the center region is small. Thus, the movement of the object is difficult to appear in the center region of the image, and the accuracy in detecting objects based on the image moving vector may be reduced.